Monday, October 30, 2006

How much attention should we give to climate change skeptics?

Well, the Stern report has now been released and provides very firm, clear conclusions. According to the report, the cost-benefit evaluation firmly indicates that we should take action now to reduce greenhouse emissions in order to prevent significantly greater costs in the future.

Inevitably, it is possible to raise concerns about the report. For instance, have the authors given enough attention to the uncertainties that exist within climate science? Secondly, how reliable are the estimates of climate change damage costs? (answer: not very reliable, but probably as reliable as we can make them).

Personally, I am generally supportive of the report's findings; they seem broadly in tune with my understanding of the literature on climate change economics. However, you can bet your bottom dollar that, as you are reading this, small teams of corporate funded climate change skeptics will be frantically reading the report, doing their best to pick holes in it, often with questionable objectivity. Such is the nature of the debate on climate change.

No doubt, in due course, these skeptics will be given radio and TV airtime and newspaper column inches as they do their best to persuade us that there is no scientific consensus on climate change. The more respectable parts of the media do their best to provide a balanced argument. If they mention the Stern report's findings, they feel they should also provide the counter arguments and give some mention of the anti-climate change position. But what if 99% of scientists believe in climate change and only 1% have doubts? In these circumstances a 'balanced' debate, in which both sides of the argument are given equal attention, could be very misleading. It seems this is the situation in which the climate change debate now finds itself (although I'm not claiming the 99:1 ratio is accurate). I'm certainly not advocating censorship but I do feel the skeptics receive a disproportionate amount of airtime and column inches.

However, I will now fuel this imbalance by referring to a critique of the first three papers prepared within the Stern review. The critique can be read here. An interesting read, but is it representative of a wider viewpoint or merely representing a minority position?

Incidentally, it is interesting to note that one of the authors of this critique is Ross McKitrick. He appears to be a passionate climate change skeptic and, along with Stephen McIntyre, questioned the existence of the 'hockey stick' graph which shows a dramatic increase in global mean temperature in recent centuries. Indeed, in the Stern critique above, the authors refer to the hockey-stick evidence as 'flawed'. Yet in response to the debate surrounding the hockey stick graph, the US National Academy of Sciences (NAS) conducted a review of the science behind the relationship. Specifically, they assessed the robustness of the work of Michael Mann et al. who published the key research on the hockey stick.

"We roughly agree with the substance of their findings"

was the conclusion of the Chair of the NAS review, although questionmarks were raised over some of Mann et al's temperature estimates for the period between 900 and 1600. The article in Nature discussing the NAS's findings can be read here

If those of us who do work relating to climate change are confused, how is the man or woman on the street meant to know which viewpoints belong to the consensus and which belong to a vocal minority? They have no chance.

8 comments:

Adam said...

Also, since the Stern report, the BBC have started to quote per person environmental cost of various activities.

This seems very odd to me. The very basic concept can be a challenge to grasp and anyone who really starts to think about what a per person environmental cost is will start to ask questions that economists have been working on for decades.

It just seems like even more science jargon being thrown around to the public and it uneases me a little.

Anonymous said...

Your report is unbalanced. The 99:1 consensus ratio, just like Michael Mann's "hockey stick" (which can not be independently replicated), is massively exaggerated.

See for example

“The scientific consensus on climate change”
The letter Science Magazine refused to publish
Letter by Benny Peiser to Science 4 january 2005

http://www.staff.livjm.ac.uk/spsbpeis/Scienceletter.htm

See also

Another Letter Science Refused To Publish
“The Not So Clear Consensus On Climate Change”
Letter by Dennis Bray submitted to Science 22 December 2004

http://w3g.gkss.de/G/Mitarbeiter/bray.html/
(delete break) BrayGKSSsite/BrayGKSS/WedPDFs/Science2.pdf

Excerpts from the Wegman Panel report:


Wegman report (page 40):

…. However, it is immediately clear that Mann, Rutherford, Jones, Osborn, Briffa, Bradley and Hughes form a clique, each interacting with all of the others. A clique is a fully connected subgraph, meaning everyone in the clique interacts with every one else in the clique.

Wegman report (page 49):

Generally speaking, the paleoclimatology community has not recognized the validity of the MM05 papers and has tended dismiss their results as being developed by biased amateurs. The paleoclimatology community seems to be tightly coupled as indicated by our social network analysis, has rallied around the MBH98/99 position, and has issued an extensive series of alternative assessments most of which appear to support the conclusions of MBH98/99.


Wegman report (page 4):

…. In this case we judge that there was too much reliance on peer review, which was not necessarily independent. Moreover, the work has been sufficiently politicized that this community can hardly reassess their public positions without losing credibility.


Wegman report (Introduction)

‘It is important to note the isolation of the paleoclimate community; even though they rely heavily on statistical methods they do not seem to be interacting with the statistical community. Additionally, we judge that the sharing of research materials, data and results was haphazardly and grudgingly done. In this case we judge that there was too much reliance on peer review, which was not necessarily independent. Moreover, the work has been sufficiently politicized that this community can hardly reassess their public positions without losing credibility. Overall, our committee believes that Dr. Mann’s assessments that the decade of the 1990s was the hottest decade of the millennium and that 1998 was the hottest year of the millennium cannot be supported by his analysis.’

Factsheet: http://energycommerce.house.gov/108/...fact_sheet.pdf

Edward Wegman's résumé
http://www.galaxy.gmu.edu/stats/facu...an.resume2.htm

Matt Cole said...

firstly I clearly state that I'm not claiming the 99:1 ratio is accurate, this is an extreme example to illustrate my general point.

Secondly, you claim my post is unbalanced. What does unbalanced mean in this context? Is it not unbalanced to claim that Mann's hockey stick cannot be independently replicated? The NAS panel seemed to have a fair degree of confidence in the estimates since 1600, which still suggests a hockey stick to me. The RealClimate guys also seem to have a significant degreee of confidence in its existence (they include Mann but many others).

But I guess the wider point behind my post is who are we meant to believe? And how can we ascertain whether the skeptics form 1% or 40%? My gut instinct tells me skeptics form a small minority, but how accurate is this? And whose answers to that question can I trust?

Anonymous said...

Your post is unbalanced in so far as you have chosen to ignore the available literature dealing with the subject of climate change consensus, electing instead to use an arbitrary "extreme example" to illustrate your point.

Hans von Storch and Nico Stehr (neither of whom can reasonably be described as skeptics) inform in Spiegel Online: "That's ... a significant number of climatologists are by no means convinced that the underlying issues have been adequately addressed. Last year, for example, a survey of climate researchers from all over the world revealed that a quarter of respondents still question whether human activity is responsible for the most recent climatic changes."

"Is it not unbalanced to claim that Mann's hockey stick cannot be independently replicated?"

No, it is not. At least 3 independent research groups have tried and failed to replicate Mann et al.'s MBH9x study... ergo, MBH9x is falsified and is thereby pronounced scientifically dead (even if the IPCC still refuse to sign its death certificate).

"The NAS panel seemed to have a fair degree of confidence in the estimates since 1600..."

To say the Earth was hotter in the late 20th Century than it was 400 years ago—when the Little Ice Age was at its coldest—is about the same as saying that it is warmer in August than it is in January.

We already KNOW, thanks to the diligent work of paleoclimatologists from other parts of the world, that—during the Hypsithermal (~6,000 BP), Roman (~2000 BP) and Medieval (~1,000 BP) warm periods—the Arctic tree-line extended between 200 kilometers and 80 kilometers further north than it does today and that trees grew at altitudes at least 200 meters higher on mountainsides - without an automobile or airplane anywhere in sight. Scandinavian redwoods, for example, now grow 10 km further north than they did in the 1970’s. But during the MWP Scandinavian redwoods grew ~80 km further north than in the late 1990's.

Surely this is evidence that all of us can trust -wouldn't you agree?

"The RealClimate guys also seem to have a significant degreee of confidence in its existence (they include Mann but many others)."

Once again: MBH9x has been falsified. The RC hockey team have a vested interest and are NOT independent (in fact they peer review each others papers, as pointed out by the Wegman panel).

"But I guess the wider point behind my post is who are we meant to believe?"

Not who but what. One has to place ones faith in the scientific method, above all else.

"And how can we ascertain whether the skeptics form 1% or 40%?"

By conducting proper surveys and analysing the results.

"My gut instinct tells me skeptics form a small minority, but how accurate is this?"

In my view, it is not particularly accurate, in this case. But in any case, real science should not have anything to do with consensus. If it did, then revolutionary theories like continental drift and plate tectonics would never have forced their way into the day light and geologist would still be talking about mythical "land-bridges" and other esoteric nonsense.

Instinct is the memory of generations and can see in the dark. In the absence of meaningful data (light), instinct is about all one has to go on. But here that is not the case.

Matt Cole said...

"Last year, for example, a survey of climate researchers from all over the world revealed that a quarter of respondents still question whether human activity is responsible for the most recent climatic changes"

so 75% of climate researchers do accept that human activity is influencing climate? That sounds like a reasonable consensus to me and is pretty much the figure I would have guessed.

You're right that consensus shouldn't influence 'real science', but surely it has to influence policy? Policy makers are in no position to ascertain which science is 'correct' and so surely have to be steered by the majority view?

Anonymous said...

I'm sorry but before I continue could you please answer the question I asked in my previous post:

We already KNOW, thanks to the diligent work of paleoclimatologists from other parts of the world, that—during the Hypsithermal (~6,000 BP), Roman (~2000 BP) and Medieval (~1,000 BP) warm periods—the Arctic tree-line extended between 200 kilometers and 80 kilometers further north than it does today and that trees grew at altitudes at least 200 meters higher on mountainsides - without an automobile or airplane anywhere in sight. Scandinavian redwoods, for example, now grow 10 km further north than they did in the 1970’s. But during the MWP Scandinavian redwoods grew ~80 km further north than in the late 1990's.

Surely this is evidence that all of us can trust -wouldn't you agree?

Matt Cole said...

"We already KNOW, thanks to the diligent work of paleoclimatologists from other parts of the world, that—during the Hypsithermal (~6,000 BP), Roman (~2000 BP) and Medieval (~1,000 BP) warm periods—the Arctic tree-line extended between 200 kilometers and 80 kilometers further north than it does today and that trees grew at altitudes at least 200 meters higher on mountainsides - without an automobile or airplane anywhere in sight. Scandinavian redwoods, for example, now grow 10 km further north than they did in the 1970’s. But during the MWP Scandinavian redwoods grew ~80 km further north than in the late 1990's.Surely this is evidence that all of us can trust -wouldn't you agree?"

well, it's evidence that climate is subject to natural variability. But no-one disputes that do they? That doesn't in any way preclude human activity from influencing climate. I'm not sure I follow your reasoning.

But I'm in no position to have a debate on the science behind climate change, I'm not a climatologist. I'm simply trying to understand who policymakers are meant to trust and to what extent the scientific consensus believes in anthropogenic climate change. I claimed that the skeptics formed a small minority and you've told me that they form 25%. As such, I still firmly believe that policy has to be steered by the majority viewpoint.

Stump said...

global warming due to human co2 emissions is crap .!!
i guess people cant fathom the fact that a volcano when it expoldes produces tons and tons of co2 emissions,more than humans can make in a hundred years or so
so watch the video then comment
http://www.jonhs.net/freemovies/great_global_warming_swindle.htm